Nerve gases detection

Gertz B. Nerve gas detected by Czechs during Gulf War. Washington Times. 7 Sep 1993. 

There are no measurements of the actual concentrations of diisopropyl methylphosphonate in groundwater at the RMA during the years of active production of the nerve gas Sarin (i.e., 1953-1957) (EPA 1989). The first actual measurements of the concentration of diisopropyl methylphosphonate in the groundwater on the arsenal and surrounding property to the north and west were made in 1974 (Robson 1981). The concentrations of diisopropyl methylphosphonate in the groundwater ranged from 0.5 g/L (analytical detection limit) to as much as 44,000 g/L near the abandoned waste disposal ponds. Diisopropyl methylphosphonate was discharged into a lined reservoir at the RMA in 1956 and was still present 20 years later in concentrations of about 400,000 g/L (Robson 1977). 

In Japan, a number of years ago, a terrorist attack with sarin killed a dozen individuals confined to a subway car out of roughly a thousand people in the nearby vicinity. Sarin has little effect on the skin, due to rapid evaporation. It is true that the Iraqis killed many Kurds with nerve gas, but the victims were unprepared, had no training, no detection devices, no masks or other protection, no antidote and no practical way to avoid the gas. None of these vulnerabilities would be the case in a conflict with American troops. 

Figure 11. 22 Colorimetric detection of nerve gas agents by oximate formation. The spectra show the progress of the reaction by the disappearance of ther /r —> tt band at 461 nm and the appearance of the product absorption at 413 nm through an isosbestic point indicating clean conversion (reproduced by permission of The Royal Society of Chemistry).

M. Noami, M. Kataoka and Y. Seto, Improved tert-butyldimethylsilylation gas chromatographic/ mass spectrometric detection of nerve gas hydrolysis products from soils by pretreatment of aqueous alkaline extraction and strong anion-exchange solid-phase extraction, Anal. Chem., 74, 4709-4715 (2002). 

Branching of the O-alkyl ester chain of organo-phosphorus compounds may introduce an asymmetric center, which together with an asymmetric substituted phosphorus atom creates a number of stereoisomers. Diastereoisomers may even be separated on a conventional capillary GC column. This is, for instance, the case with the nerve gas soman, which usually produces two peaks in a gas chromatogram. Although this is characteristic for identifying soman, it also increases the GC/MS detection limit by a factor of two. 

Tsuge, K., Seto, Y. (2006). Detection of butyrylcholinesterase-nerve gas adducts by liquid chromatography-mass spectro-metric analysis after in gel chymotryptic digestion. J. Chromatogr. B 838 21-30. 

Naomi et al(2002) have reported a method of detection of hydrolysis products of nerve gas present in soil. The method involves extraction with an alkali, followed by an ion-exchange pretreatment of the aqueous soil extract and derivatization to tert-butyldi-methylsilyl derivatives. The derivatives of alkylmethylphosphonic acid and methylphos-phonic are analyzed by GC-MS. 

The M8 and M9 detection papers provide rapid (<1 minute), inexpensive tests for the presence of liquid mustard or nerve agents. Use of the paper is a screening test only, and results must be verified with more accurate methods of detection, particularly because of the paper s propensity to show false positive results for substances such as petroleum products and antifreeze. False positives are especially undesirable in a civilian context, where the mere rumor of "nerve gas" may cause hysteria. 

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